We simply ask for people to follow basic standards of civil conduct on public forums, including boards, channels, and populated areas. We would prefer that players act in a mature fashion under their own free will, but if an argument reaches the point where it spills over into public places and is spoiling everyone's enjoyment of the mud, we will become involved. If you have a problem with somebody, we ask that you just try to avoid contact with them.
Taking an argument to Tells might help, but harassment can be private just as well as public. Generally, if somebody asks you to stop doing something, stop. The "ignore" command exists precisely to help deal with this kind of harassment, so please use it before you ask for Immortal intervention.
Sexual harassment of any kind is not acceptable.
Keep in mind that mud etiquette exists alongside mud rules. Yelling (using all caps) and generally being obnoxious are among the things frowned upon; a bit of common sense goes a long way in avoiding this stuff. Such rude gestures are extremely poor ways to make friends, and a pattern of consistent inconsiderate behavior can push the borders of "civil conduct."
On a related note, please keep material on the message boards relevant to the board's intended content.